Aldrin has not been adequately tested in the
Hastings area.
Precautions.-When using insecticides be care-
ful not to spill the material on any part of the
body or to breathe spray mists, vapors or dusts.
Always read and observe cautions on labels.

DISEASES AND CONTROLS
Late Blight.-Nabam (27 %)-2 qts. plus :3 to
1 lb. zinc sulfate per 100 gallons.- Zineb (65%)--
2 Ibs. per 100 gallons.
In southern parts of the state begin applications
of spray for late blight when plants have emerged
and continue at four- to five-day intervals. In
the Hastings area begin when the. plants are 6
to 8 inches high, if late blight does not show
earlier and continue at four- to five-day intervals.
At Belle Glade and Homestead late blight is
usually present throughout the growing season
and nothing less than the best fungicide applied
on a rigid schedule gives satisfactory control.
Complete coverage is essential.
Early Blight.-Nabam-zine sulfate spray as
recommended for control of late blight will also
control early blight.
Scab.-Treat seed with hot or cold forinalde-
hyde solution or acidulated mercuric chloride so-
lution in areas where soil reaction is usually pH
6.0 or higher. Do not treat seed when potatoes
are to be grown in areas where scab has caused
little trouble.
(1) Cold Formaldehyde-1 pt. 40% in 30 gal-
lons water.
Soak uncut tubers 11/2 hours, then remove and
air out thoroughly. This treatment is more effec-
tive when sacked tubers are first soaked in water
for 2 minutes before soaking them in formalde-
hyde or mercury solutions. This softens the scab
lesions.
(2) Hot Formaldehyde--3.3 qts. 40% per 100
gallons water.
Dip uncut sacked tubers for 3 to 4 minutes in
the solution held at 1220 1240F. Stack sacks on
end to dry.
Potatoes may be cut for planting any time after
the sacks have dried.

Temperature of the hot solution must be kept
within the range indicated to give control of the
disease without injuring the tubers.
(3) Acidulated Mercuric Chloride-6 oz. mer-
curic chloride plus 1 qt. commercial HCI in 25
gallons water.
Soak sacked uncut tubers for 5 minutes, allow
to drip and plant immediately, or dry out. This
treatment is safe for potatoes planted on sandy
and marl soils, but not safe on muck and peat
soils. This material is poisonous and corrosive
and treated seed should not be eaten or fed to
livestock.
Sclerotinia.-On marl soils, where sclerotinia
has been observed in the previous crop, apply
400 to 600 pounds of cyanamid per acre before
planting. It should be evenly distributed and
thoroughly mixed with the surface soil.

DORMANCY
Chemical treatment for breaking the "rest
period" of the potato tuber is not recommended,
except for the fall-planted crop in the Everglades.
In those cases where the need has been estab-
lished, the following is one of several methods
recommended: Dip boxes of freshly-cut seed-
pieces in a solution of ammonium thiocyanate
used at the rate of 3 pounds in 50 gallons of water;
allow them to drain and stack loosely in well
ventilated sheds. Avoid temperatures above
800F. during cutting and treating. Plant treated
seed pieces following day.

HARVESTING
Vine-Killing.-Most early potatoes in Florida
are harvested at an immature stage. In handling
and transit the potato may skin badly. By kill-
ing vines about 10 days before harvesting, the
skin is allowed "to set". Vines can be killed by
mechanical means or by the use of chemical vine-
killers such as the dinitro compounds.
Handling.-Care should be exercised in digging,
gathering, loading, grading, etc., to prevent
mechanical injuries to the potatoes. It is advis-
able to prevent over-exposure to sunlight.

Circular 118 September 1953

COOPERATIVE EXTENSION WORK IN
-AGRICULTURiiE ,ANID HOMIE ECONOMICS
(Acts of May 8 and June 30. 1914)
Agricultural Extension Service, University of Florida,
Florida State University and
United States Department of Agriculture. Cooperating
H. G. Clayton, Director

POTATO PRODUCTION

GUIDE
(Prepared in cooperation with workers of the
Florida Agricultural Experiment Stations)

Production practices are subject to rapid change
by new problems arising and the application of
research results to meet these needs. No attempt
is made here to foresee all the complications pos-
sible, but instead to present the current pertinent
facts on potato production. Experienced growers
may have several modifications of these practices
for their specific conditions.
Additional information is available in several
publications of the University of Florida Agri-
cultural Experiment Stations, including (1) Cir.
S-25, (2) Bul. 352, (3) Bul. 427, (4) Bul. 472
and (5) Bul. 504. The supply of a given publica-
tion for distribution may be irregular. For cur-
rently available publications and for further de-
tails on local problems, contact your County Agri-
cultural Agent of the University of Florida Agri-
cultural Extension Service.

AGRICULTURAL EXTENSION SERVICE
GAINESVILLE, FLORIDA

FLORIDA AND LEADING COUNTIES' HARVESTED
ACREAGE 1951-52: 29,800 ACRES TOTAL

KENNEBEC.-White. Skin slightly russeted.
High yielder. Resistant to late blight, but does
not have proven shipping and chipping qualities.
For home garden use only.
KATAHDIN.-White. A former commercial
variety of high quality. For home garden use
only.

Most of the North Florida commercial crop is
planted to Sebago. In South Florida the red po-
tatoes are generally grown.
Certified seed only should be planted. It is
produced under the supervision of certification
agencies and is true as to variety and contains
no more than the tolerances allowed for the worst
seed-borne diseases.

PLANTING
DISTANCES
Between rows:
36" to 42" general
Between plants:
10" to 14" general but
6" to 9" South Florida

Wireworms Chlordane at 4 lbs. or aldrin at 3 lbs. active
ingredient per acre sprayed on the soil sur-
face and disked in prior to planting.

For the Hastings area DDT emulsion applied
in a regular schedule at intervals of 10 days to
2 weeks will control most potato insect pests, in-
cluding aphids. Thus, where leaf miners, stink
bugs, other plant bugs and armyworms are not
a problem, DDT emulsion alone is a satisfactory
potato insecticide for this area. It is not felt that
TEPP is necessary for insect control in the Hast-
ings area.
In the Homestead area parathion applied in a
regular schedule of 7 to 10 days has controlled
potato insects.
Dusts should be applied at a rate of 20 to 30
pounds per acre and sprays at a rate of 75 to 150
gallons per acre, depending on the size of plants.

FERTILIZATION
Best results usually are obtained by applying
fertilizers in two bands, each band located 2 to 3
inches below and 3 to 4 inches to the side of the
seed pieces.
Where manganese deficiency develops, two or
three sprays containing 2 pounds of manganese
sulfate per 100 gallons of water usually are cor-
rective, or 2.0 % MnO may be applied in the fertil-
izer in areas (pH above 6.0) where manganese
deficiency is likely to occur. Copper deficiency on
muck may be controlled by 1.0% CuO per ton of
fertilizer applied prior to planting.
Side-dress with 100 to 150 pounds of nitrate
of potash or nitrate of soda per acre on sandy
soils, especially in seasons when heavy, leaching
rains occur soon after planting.
Soil Type Fertilizer Pounds per Acre
Marl 2-8-6 or 4-8-6 1,200 -1,800
0-10-10** 500 -1,000
Muck and Peat 0-8-24 750
Sand* 5-7-5 or 6-8-8 2,300
In the Hastings area it is advisable to adjust soil acidity to pH
5.5 and supply one-fifth of the nitrogen from nitrate sources.
** When cyanamid is used at the rate of 400-600 pounds per acre
to control sclerotinia, it supplies sufficient nitrogen for the crop.

For new, sandy soil or areas where leaf-roll has
been observed, side-dressing with nitrate-nitrogen
40 to 60 days after planting is advisable. The
proportion of nitrate-nitrogen in the fertilizer
mixture should be increased up to one-third of
the total nitrogen.